Process for preparing urethane/acrylic-or-vinyl latexes

Claim 1

A process for preparing a polymeric urethane/acrylic-or-vinyl latex, in which the urethane polymer component has no urea linkages, comprising the sequential steps of: 1) providing an acrylic or vinyl monomer that is (i) unreactive with free isocyanate functionality, (ii) polymerizable in the presence of a free radical initiator, and (iii) an effective solvent for the resultant urethane polymer; 2) adding to the acrylic or vinyl monomer in the absence of a free radical initiator the following compounds in amounts such that the molecular ratio of isocyanate groups to active hydrogen atoms is about 1 to 1: (a) one or more polyisocyanates, (b) one or more organic compounds each containing at least two active hydrogen atoms attached to oxygen, and (c) one or more hydrophilic organic compounds, each containing at least two active hydrogen atoms attached to oxygen and present an a sufficient amount to render the resulting polyurethane emulsifiable, selected from the group consisting of a polyethylene glycol characterized by the structure H(OCH 2 CH 2 ) x OH in which x is an integer from 13 to 450, dimethylolpropane carboxylic acid, N-methyl diethanoldiamine, N-ethyldiisopropanolamine, the quaternary reaction product of N-methyl diethanoldiamine with dimethyl sulfate or methyl halide, and the quaternary reaction product of N-ethyldiisopropanolamine with dimethyl sulfate or methyl halide; 3) heating the resultant mixture from step 2) to a temperature in the range of 25° to 120° C. for about 1-10 hours to form a fully reacted polyurethane; 4) adding a sufficient amount of a C 1 -C 4 alkyl alcohol to consume any residual isocyanate functionality; 5) emulsifying in water the fully reacted polyurethane and acrylic or vinyl monomer; 6) adding a free radical initiator to the resulting emulsion; and 7) polymerizing the acrylic or vinyl monomer using free radical polymerization procedures.